Apply fixes in ena-com

Apply fixes in ena-com

* Change ena-com BIT macro to work on unsigned value.
  To make the shifting operations safer, they should be working on
  unsigned values.

* Fix a mutex not owned ASSERT panic in ENA control path.
  A thread calling cv_broadcast()/cv_signal() must hold the mutex used for
  cv_wait(). Fix the ENA control path code that has this problem.

Submitted by:   Krishna Yenduri <kyenduri@brkt.com>
Reviewed by:    Michal Krawczyk <mk@semihalf.com>
Tested by:      Michal Krawczyk <mk@semihalf.com>